Color flat panel displays, such as liquid crystal displays and the like, typically incorporate color filters used to provide pixels with color. One technique for fabricating color filters involves a laser-induced thermal transfer process. A particular prior art thermal transfer process is illustrated schematically in FIG. 1. A substrate 10, known in the art as a receiver element, is overlaid with a donor element 12, known in the art as a donor sheet. Donor element incorporates a transferable donor material (not shown) that may comprise a colorant, a pigment, or the like used to fabricate the color filter.
Donor element 12 is image-wise exposed to cause donor material to be transferred from selected portions of donor element 12 to a surface of substrate 10. Some exposure methods employ one or more controllable lasers 14 to provide one or more corresponding laser beams 16 to induce the transfer of donor material from the imaged regions of donor element 12 to corresponding regions of substrate 10. Controllable laser(s) 14 may comprise diode laser(s) which are relatively easy to modulate, are relatively low cost, and are relatively small in size. Such laser(s) 14 are controllable to directly expose donor element 12. In some applications, masks (not shown) are used in exposing various media.
In some imaging applications, a number of different donor elements 12 are sequentially applied to substrate 10, imaged and then removed. For example, during typical fabrication of color filters, a first donor element 12 is used to apply one color, such as a red donor material to substrate 10, and the first donor element is then removed; a second donor element 12 is used to apply, for example, green donor material, and the second donor element is then removed; a third donor element 12 is used to apply, for example, blue donor material, and the third donor element is then removed.
Media loaders employing various cylindrical supports such as rollers and the like are typically employed to apply or remove flexible media such as donor element 12 to or from various surfaces. The various rollers are required to perform various operations which include but are not limited to: the transferring and loading of media into the loader, the application of media onto a surface, and the removal of media from the surface after it has undergone a processing step (e.g. imaging). Each of these operations requires roller alignments suitable for that given operation. For example, in some processes the media is stored on media rolls and a web of media is transferred from a media roll to a roller of the media loader during a loading operation. The loading operation can involve separating the media web into sheets of media. Accurate alignment between the media roll and the roller is required to ensure substantially uniform web tension to avoid the formation of wrinkles during loading. Web tension is related to the amount of force applied in the direction of travel of the web. Excessive tension can cause slippage, damage media coating(s) or even deform the web itself. Insufficient web tension can lead to wrinkles forming in the web. The difficulties associated with the loading operation can be further compounded when media is loaded from a plurality of media rolls (e.g. different colored donor elements) and each of the media rolls has a different orientation with respect to the roller sufficient to alter the web tension between the different loadings.
Imaging processes such as thermal transfer are typically sensitive to the uniformity of the interface between the applied donor element 12 and a substrate 10. Entrapped bubbles, wrinkles and the like can cause variances in the amount of donor material that is transferred to substrate 10 which can lead to various undesired image artifacts. Media that has been loaded into the media loader typically needs to be applied to substrate 10 such that a uniform interface free of wrinkles, air bubbles, etc, is created between the donor element 12 and substrate 10. Donor element 12 can be applied by a roller of the media loader (e.g. an application roller). Donor element 12 can be applied by relatively translating the media loader along an application direction while rolling donor element 12 onto substrate 10. Misalignment between the application roller and the application direction can lead to wrinkles and uneven application.
Once imaged, the spent donor element 12 is removed from substrate 10. Donor element 12 is typically removed by various rollers of the media loader (e.g. a peel roller). Donor element 12 is removed by relatively translating the media loader along a removal direction while peeling the donor element 12 away from substrate 10. Misalignment between the peel roller and the removal direction can lead to various image artifacts. For example, skew between the peel roller and the removal direction can cause shear forces that may degrade the quality of the formed image.
It now becomes apparent to those skilled in the art that various rollers within such media loaders can require different orientations for different operations thereby leading to possible conflicts. These conflicts may possibly be remedied by adopting onerous manufacturing tolerances but with an undesired increase in the cost of the device.
What is needed in the art is a media loader having one or more cylindrical rollers in which an orientation thereof can be adjusted in accordance with a specific operation required of the loader. Such operations can include loading media into the loader, applying media to a surface and removing media from a surface.
What is needed in the art is an imaging device that includes a media loader having one or more cylindrical rollers whose alignment can be adjusted in accordance with a specific function required of the media loader. The media is imaged with an imaging process that can include a thermal transfer imaging process.